Signaling system.



(No Model.)

L. B. SMITH.

SIGNALING SYSTEM.

(Application filed Apr. 27, 189B.)

Patented May 29, I900.

Enduefioam.

Z'aremqzz m: NORRIS Pmns ca. Puma-Mme.v wasmumom u. 04

//v VENTOH A TTORNEIS UNITED STATES PATENT Genres.

LESTER C. SMITH, OF TORRINGTON, CONNECTICUT.

$|GNAL|NG SYSTEM.

SPECIFICATION forming part of Letters Patent No. 650,570, dated May 29, 1900.

Application filed April 27, 1898. Serial No. 678,988. (No mocleL) To all whom it may concern:

Be it known that I, LESTER. 0. SMITH, 0t Torrington, in the county of Litchfield and State of Connecticut, have invented a new and Improved Telephone Signaling System, of which the following is a full, clear, and exact description.

The invention relates to telephone systems operated without the use of a central station.

The object of the invention is to provide a new and improved telephone signaling system more especially designed for use in factories, shops, stores, and other buildings and places and arranged to enable a person at one of the local stations in the system to call up another person at any one of the other stations at or near which the second person happens to be at the time.

The invention consists of novel features and parts and combinations of the same, as will be fully described hereinafter and then pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the figures.

Figure 1 is a diagrammatic view of theimprovement with a number of stations and one of the stations enlarged. Fig. 2 is a diagrammatic view of the improvement with two stations, with the receivers and transmitters omitted; and Fig. 3 is a face view of part of the call-card. I V

The improved telephone system is provided with a plurality of stations A A A A distributed over a building or buildings or other places and electrically connected with each other by three wires B, B, and B of which the wire 13 contains the batteries B and forms the series line,while the wires B and B form parallel lines in contradistinction to the series line. Each of the local stations is provided with a transmitter 0, receiver D, and a call-bell, buzzer, or like sounding device E, having a push-button E',connected by the wires E and E with two wires B and B respectively. The wire B is connected at B with the wire B and at the other end at B with the wire 13 as plainly shown in Fig. 2. It is evident that by connecting the parallel lines or wires 13 and B with each other through a pushbutton E, for instance, the circuit is closed and bells orbuzzers are sounded according to a predetermined arrangement, as indicated 'on the call-card. (Shown in Fig. 3.) On the other hand, if the wire B is parted for telephone purposes by removing the receiver D from the hook of the switch-lever F then the wires B and B become separate wires, having no electrical connection through the signaling apparatus, and are now qualified to act in whole or in part as the two wires of a telephonic transmission-line. It will be fur-. ther noticed that the parting of the wire 13 at any point must of necessity render the same inoperative, owing to the fact that no current can go through the wire when parted. Hence the person desiring to signal another is en abled to ascertain whether the system is in use at the time or not, as no bell or buzzer will operateif by the removal of the receiver from the switch-leverF the wire is parted. A switch-lever F at each station is adapted to support the corresponding receiver D, so as to hold said switch-lever in such a position as to close and complete the circuit containing the call-bell E, the switch-lever F being provided with an insulated point F, adapted to close the circuit for the receivers and transmitters at the time the receiver is taken off the switch-lever and the latter moves into the position shown in the enlarged portion of Fig. 1.

Now it is evident that by the arrangement described a person at one of the stations can readily send predetermined elementary mo tions to the several call-bells in the system by pressing the push-button E of this station accordingly, the several bells sounding in unison,'according to the elementary motions given upon pressing the push-button. Thus assuming that station A is the office and is represented by two elementary motions, a

'dash and a dot, as shown in Fig. 2, the enginearticulate speech by the transmitters and receivers. When the conversation is ended,

the transmitters O are replaced on-the switch levers F to throw the transmitters and receivers in the entire system out of circuit and to again throwthe call-bells into circuit. The system is now again in order for another call. For instance, if one of the employees or other person desires ,to connect. with the office and is located near station A he presses the push-button E at this station to produce dash-and-dot elementary motions, so-that the several call-bells in the system sound corre-.

spondingly, and the person in charge of station A, which is in the office, steps to the telephone, removes the receiver D, and thereby throws the callbells out of action, as previously explained, and opens conversation with the person that called the office.

It is evident that by the arrangement described signals may be provided for a large number of persons greatly in excess to the number of stations, as it is not necessary that i a station 'be provided for each signal, as all the stations sound the same signals, and only the person whose signal has been sounded responds at the nearest telephone-station. From the foregoing it will also be seen that conversation is always along the nearest pos-.

sible route. For instance, if parties at stations A and A are conversing the line-wires l3 and 13 between these stations only are active, other instruments between or beyond being out of circuit by means of the position of their switch-levers F, maintained by the weight of their receivers. Hence conversation, owing to the absence of all unnecessary wire in circuit, is much plainer than in parallel bell systems, where it is necessary to talk through great lengths of wire contained in the relays necessary for the operation of the bells.

The series bells and buzzers made necessary by this system or any series system or any high-po'tential system differ in no respect from the ordinary vibrating bell or buzzer, but have a shunt E, (see call-bell E at station A,) properly proportioned to their coils an d spark-gap, placed across their terminals. The necessity for the shunt is as follows:

' First. A long length of line and large number of bells or buzzers in series requires a high electromotive force that the current necessary to the operation 01": an extensive system may be caused'to pass through it, (see call-bell E at station A, which rep-resents an ordinary vibrating bell or buzzer in which the armature K is caused'to vibrate in the ordinary manner by an intermittent current which traverses the electromagnet L,) said current being made intermittent by the action of the armature in closing and breaking the circuit, according to its position, at the point of the set-screw N, forming at this point a spark Whose destructiveness is determined by the electromot-ive force of the current traversing the line of which it is a part. As this electromotive force may be considerable,aspreviouslyexplained, it follows that the hell or buzzer is soon destroyed. The shunt E remedies this defect by having-a re-' sistance so low, as compared to the sparkgap at the point of theset-screw-N, as to take the .whole current the instant this gap is formed, thereby'cutting out the spark. At I the same time its resistance is sufficientlyhigh to drive the major portion of the current through the eleetromagnet L when the circuit at the set-screw N is closed, thereby operating the bell or buzzer.

Secondly. As previously explained, a series line is. rendered inoperativeby a gap at any point. Hence the gap at the point of the set-screw N in the ordinary vibrating bell or buzzer-t. a, without a shunt-constituting,

as it does, a gap in the line, causes bells or buzzers in the act of making a stroke to lose their energy and owing to the intermittent character of the current to vibrate by spasms or not at all and to transmit no intelligible signal. The shunt removes thisdifficultyby keeping the circuit complete at all times, its resistance being so low, as compared with the total circuit, as to allow practically the entire current to traverse it when the bell or buzzer to which it is attached has its magnets cut out by'action of the armature, as previously explained. r

.If a large number of batteries be placed in the wire 13 and the bells or buzzers they are the wire B at any point for rendering the a whole system of bells inoperative, should the same be desired. 7

I do not limit myself to theparticular arrangement described, as it is evident that my three-wire system described can be readily used with other telephones or signaling devices.

Having thus'fully described my invention,

I claim as new and desire to secure by'Letters Patent-- 1. A telephone system provided with a plurality of local stations each containing a re= ceiver, a transmitter, and a call-bell, a series line containing the batteries and including the call-bells, twoparallel lines, one of which is connected with one end of the series line and the other of which is connected with the other end of the series line, and switch-levers in the series line and adapted to hold the receivers, said levers being adapted to break the circut in the series line to separate the parallel lines with respect to the call-bells, as and for the purpose set forth.

2. A telephone system provided with a plurality of local stations, each containing a receiver, a transmitter, a call-bell, and a shunt bridging the terminals of the call-bell, a series LESTER C. SMITH.

Witnesses:

THEO. G. I-IosTER, J NO. M. BITTER. 

